. The electric and
magnetic deflections give two independent measurements which may be made
on a cathode ray, and both the deflections involve theoretically three
unknown quantities, the mass of the particles, their electric charge
and their velocity. There is strong cumulative evidence that all
such particles possess the same charge, which is identical with that
associated with a univalent atom in electrolytic liquids. The number of
unknown quantities was thus reduced to two--the mass and the velocity.
The measurement of the magnetic and electric deflections gave two
independent relations between the unknowns, which could therefore be
determined. The velocities of the cathode ray particles were found to
vary round a value about one-tenth that of light, but the mass was found
always to be the same within the limits of error, whatever the nature of
the terminals, of the residual gas in the vessel, and of the conditions
of the experiment. The mass of a cathode ray particle, or corpuscle, as
Thomson, adopting Newton's name, called it, is about the eight-hundredth
part of the mass of a hydrogen atom.

These corpuscles, found in so many different kinds of substance,
are inevitably regarded as a common constituent of matter. They are
associated each with a unit of negative electricity. Now electricity in
motion possesses electromagnetic energy, and produces effects like those
of mechanical inertia. In other words, an electric charge possesses
mass, and there is evidence to show that the effective mass of a
corpuscle increases as its velocity approaches that of light in the way
it would do if all its mass were electromagnetic. We are led therefore
to regard the corpuscle from one aspect as a disembodied charge of
electricity, and to identify it with the electron of Lorentz and Larmor.

Thus, on this theory, matter and electricity are identified; and a great
simplification of our conception of the physical structure of Nature is
reached. Moreover, from our present point of view, a common basis for
matter suggests or implies a common origin, and a process of development
possibly intelligible to our minds. The idea of the evolution of matter
becomes much more probable.

The question of the nature and physical meaning of a corpuscle or
electron remains for consideration. On the hypothesis of a universal
luminiferous aether, Larmor has suggested a centre of aethereal strain
"a place where the continuity of the medium has been bro